Structural Controls on Himalayan Glacial Lake Expansion

2021 ◽  
Author(s):  
Matthew Peacey ◽  
Tom Holt ◽  
Neil Glasser ◽  
John Reynolds
Keyword(s):  
Distinct Pattern ◽  
Glacial Lake ◽  
Lake Area ◽  
Terminal Moraine ◽  
Existing Structures ◽  
Flow Units ◽  
Glacier Recession ◽  
Outburst Floods ◽  
Glacier Flow ◽  
The Himalaya

<p>As glaciers in the Himalaya have lost mass, their proglacial lakes have expanded. Despite increasing interest in hazard assessment and mitigation of Glacial Lake Outburst Floods (GLOFs) over more than the last two decades, the role of glacier structures in controlling patterns and rates of glacier recession, and subsequently of lake expansion, have not yet been investigated in detail. This study aims to identify and map glacier structures over a 20-year period and investigate their significance in ice front recession. Four glacial lakes and their associated debris-covered glaciers have been examined in the Everest Region of Nepal and China: Imja Tsho, Tsho Rolpa, Lumdin Tsho, and Dang Pu Tsho. Lake area was mapped between 2000 and 2020 using images acquired from Landsat 5/7/8 and Sentinel 2. Discrete glacier flow units were identified and specific structures were digitised using the finest-resolution panchromatic bands. We reveal a distinct pattern of transverse features across each glacier that can be related to ice frontal position through time. While this is not the only controlling factor contributing towards ice front recession from lake-terminating glaciers in the Himalaya, it is clear that pre-existing structures influence the ice front shape and are involved in ice front deterioration. These observations could be used to indicate future ice front positions and behaviour, and rates of glacier recession and of lake expansion.  This would also enable GLOF hazard assessments to include more detailed glaciological factors and help in the recognition of such legacy structures in the behaviour of stagnant debris-covered ice masses that are part of terminal moraine complexes.</p>

Role of supraglacial lakes in recession of Himalayan glaciers: A case study of Dudh Koshi basin, Nepal

2018 ◽  
Vol 12 (3) ◽  
pp. 199-207 ◽  
Author(s):  
Florencia Matina Tuladhar ◽  
Diwakar KC
Keyword(s):  
Interannual Variation ◽  
Google Earth ◽  
Glacial Lake ◽  
Coefficient Of Determination ◽  
Lake Area ◽  
Supraglacial Lakes ◽  
Glacier Recession ◽  
Outburst Floods ◽  
Koshi Basin

Abstract Climate change has been adversely affecting glaciers causing them to advance and recession worldwide. Existing studies have primarily attributed temperature as the leading factor causing glacier recession. However, detailed studies that investigate effect of other factors like presence of debris cover, slope, and contact with water bodies are still scarce. This research, thus investigated the role of supraglacial lakes in recession of debris-covered glaciers (DCG). Such glaciers were studied since these lakes are found in debris-covered glaciers only. For this purpose the interannual variation in area of supraglacial lakes of Dudh Koshi basin was computed to test the hypothesis that these lakes play a significant role in glacier recession. Supraglacial lakes were delineated using Google Earth Pro at five year intervals to assess interannual variation in lake area. Slope, elevation and change in supraglacial lake area were the predictors influencing average decadal change in area of glaciers. Two models prepared using multiple linear regression in Excel were compared. The first model used elevation and slope as predictors while the second model used change in supraglacial lake area as the additional predictor. The second model had a higher coefficient of determination (R square) and Adjusted R-square values of 99 % and 96 % compared to the first model. Further test statistics from Analysis of Variance (ANOVA) results were compared to test the hypothesis. Moreover the Root mean square error (RMSE) of second model was also less than the first one. Hence both the regression statistics and RMSE confirmed that change in area of supraglacial lakes was an important factor that influences overall recession of debris-covered glaciers. Nevertheless, use of high spatial and temporal resolution imageries along-with increase in number of glaciers sampled should be incorporated in future studies to ensure robust outcomes. Thus this research can bolster the overall understanding between glacier and glacial lake dynamics which will improve the resilience of downstream inhabitants from climate induced hazards, such as glacial lake outburst floods (GLOFs).

What’s in a lake? Glacial Lake Outburst Floods in the Peruvian Andes.

2021 ◽  
Author(s):  
Joanne Wood ◽  
Stephan Harrison ◽  
Ryan Wilson ◽  
Neil Glasser ◽  
John Reynolds ◽  
...  
Keyword(s):  
Climate Change ◽  
Glacial Lake ◽  
Peruvian Andes ◽  
The Past ◽  
The Andes ◽  
Glacier Recession ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Lake Systems ◽  
Physical Components

<p>Climate change is resulting in mass loss and the retreat of glaciers in the Andes, exposing steep valley sides, over-deepened valley bottoms, and creating glacial lakes behind moraine dams. Glacial Lake Outburst Floods (GLOFs) present the biggest risk posed by glacier recession in Peru. Understanding the characteristics of lakes that have failed in the past will provide an aid to identifying those lakes that might fail in the future and narrow down which lakes are of greatest interest for reducing the risks to local vulnerable populations. </p><p>Using a newly created lake inventory for the Peruvian Andes (Wood et al., in review) and a comprehensive GLOF inventory (unpublished) we investigate lakes from which GLOFs have occurred in the past. This is to establish which physical components of the glacial lake systems are common to those lakes that have failed previously and which can be identified remotely, easily and objectively, in order to improve existing methods of hazard assessment.</p>

scholarly journals Reconstructing the History of Glacial Lake Outburst Floods (GLOF) in the Kanchenjunga Conservation Area, East Nepal: An Interdisciplinary Approach

2020 ◽  
Vol 12 (13) ◽  
pp. 5407
Author(s):  
Alton C. Byers ◽  
Mohan Bahadur Chand ◽  
Jonathan Lala ◽  
Milan Shrestha ◽  
Elizabeth A. Byers ◽  
...  
Keyword(s):  
Interdisciplinary Approach ◽  
Debris Avalanche ◽  
Field Investigation ◽  
Glacial Lake ◽  
High Mountain ◽  
Lateral Moraine ◽  
Conservation Area ◽  
Terminal Moraine ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods

An interdisciplinary field investigation of historic glacial lake outburst floods (GLOFs) in the Kanchenjunga region of Nepal was conducted between April and May, 2019. Oral history and field measurements suggested that at least six major GLOFs have occurred in the region since 1921. A remote sensing analysis confirmed the occurrence of the six GLOFs mentioned by informants, including two smaller flood events not mentioned that had occurred at some point before 1962. A numerical simulation of the Nangama GLOF suggested that it was triggered by an ice/debris avalanche of some 800,000 m3 of material, causing a surge wave that breached the terminal moraine and released an estimated 11.2 × 106 m3 ± 1.4 × 106 m3 of water. Debris from the flood dammed the Pabuk Khola river 2 km below the lake to form what is today known as Chheche Pokhari lake. Some concern has been expressed for the possibility of a second GLOF from Nangama as the result of continued and growing landslide activity from its right lateral moraine. Regular monitoring of all lakes and glaciers is recommended to avoid and/or mitigate the occurrence of future GLOF events in the region. Collectively, the paper demonstrates the benefits and utility of interdisciplinary research approaches to achieving a better understanding of past and poorly documented GLOF events in remote, data-scarce high mountain environments.

Unchanged frequency of moraine-dammed glacial lake outburst floods in the Himalaya

2019 ◽  
Vol 9 (5) ◽  
pp. 379-383 ◽  
Author(s):  
Georg Veh ◽  
Oliver Korup ◽  
Sebastian von Specht ◽  
Sigrid Roessner ◽  
Ariane Walz
Keyword(s):  
Glacial Lake ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
The Himalaya

scholarly journals Climate change and the global pattern of moraine-dammed glacial lake outburst floods

2017 ◽  
Author(s):  
Stephan Harrison ◽  
Jeffrey S. Kargel ◽  
Christian Huggel ◽  
John Reynolds ◽  
Dan H. Shugar ◽  
...  
Keyword(s):  
Climate Change ◽  
Ice Age ◽  
Dam Failure ◽  
Glacial Lake ◽  
Glacier Recession ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Lake Formation ◽  
Recent Climate ◽  
Moraine Dam Failure

Abstract. Despite recent research identifying a clear anthropogenic impact on glacier recession, the effect of recent climate change on glacier-related hazards is at present unclear. Here we present the first global spatio-temporal assessment of glacial lake outburst floods (GLOFs) focusing explicitly on lake drainage following moraine dam failure. These floods occur as mountain glaciers recede and downwaste and many have an enormous impact on downstream communities and infrastructure. Our assessment of GLOFs associated with the collapse of moraine-dammed lakes provides insights into the historical trends of GLOFs and their distributions under current and future global climate change. We observe a clear global increase in GLOF frequency and their regularity around 1930, which likely represents a lagged response to post-Little Ice Age warming. Notably, we also show that GLOF frequency and their regularity – rather unexpectedly – has declined in recent decades even during a time of rapid glacier recession. Although previous studies have suggested that GLOFs will increase in response to climate warming and glacier recession, our global results demonstrate that this has not yet clearly happened. From assessment of the timing of climate forcing, lag times in glacier recession, lake formation and moraine dam failure, we predict increased GLOF frequencies during the next decades and into the 22nd century.

scholarly journals Climate change and the global pattern of moraine-dammed glacial lake outburst floods

2018 ◽  
Vol 12 (4) ◽  
pp. 1195-1209 ◽  
Author(s):  
Stephan Harrison ◽  
Jeffrey S. Kargel ◽  
Christian Huggel ◽  
John Reynolds ◽  
Dan H. Shugar ◽  
...  
Keyword(s):  
Climate Change ◽  
Ice Age ◽  
Dam Failure ◽  
Glacial Lake ◽  
Glacier Recession ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Lake Formation ◽  
Recent Climate ◽  
Moraine Dam Failure

Abstract. Despite recent research identifying a clear anthropogenic impact on glacier recession, the effect of recent climate change on glacier-related hazards is at present unclear. Here we present the first global spatio-temporal assessment of glacial lake outburst floods (GLOFs) focusing explicitly on lake drainage following moraine dam failure. These floods occur as mountain glaciers recede and downwaste. GLOFs can have an enormous impact on downstream communities and infrastructure. Our assessment of GLOFs associated with the rapid drainage of moraine-dammed lakes provides insights into the historical trends of GLOFs and their distributions under current and future global climate change. We observe a clear global increase in GLOF frequency and their regularity around 1930, which likely represents a lagged response to post-Little Ice Age warming. Notably, we also show that GLOF frequency and regularity – rather unexpectedly – have declined in recent decades even during a time of rapid glacier recession. Although previous studies have suggested that GLOFs will increase in response to climate warming and glacier recession, our global results demonstrate that this has not yet clearly happened. From an assessment of the timing of climate forcing, lag times in glacier recession, lake formation and moraine-dam failure, we predict increased GLOF frequencies during the next decades and into the 22nd century.

scholarly journals Reconstructing historic Glacial Lake Outburst Floods through numerical modelling and geomorphological assessment: Extreme events in the Himalaya

2014 ◽  
Vol 39 (12) ◽  
pp. 1675-1692 ◽  
Author(s):  
Matthew J. Westoby ◽  
Neil F. Glasser ◽  
Michael J. Hambrey ◽  
James Brasington ◽  
John M. Reynolds ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Extreme Events ◽  
Glacial Lake ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
The Himalaya

Glacial lake outburst floods as drivers of fluvial erosion in the Himalaya

Science ◽  
2018 ◽  
Vol 362 (6410) ◽  
pp. 53-57 ◽  
Author(s):  
Kristen L. Cook ◽  
Christoff Andermann ◽  
Florent Gimbert ◽  
Basanta Raj Adhikari ◽  
Niels Hovius
Keyword(s):  
Glacial Lake ◽  
Outburst Flood ◽  
Fluvial Erosion ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Seismic Records ◽  
Glacial Lake Outburst Flood ◽  
The Himalaya ◽  
Annual Summer

Himalayan rivers are frequently hit by catastrophic floods that are caused by the failure of glacial lake and landslide dams; however, the dynamics and long-term impacts of such floods remain poorly understood. We present a comprehensive set of observations that capture the July 2016 glacial lake outburst flood (GLOF) in the Bhotekoshi/Sunkoshi River of Nepal. Seismic records of the flood provide new insights into GLOF mechanics and their ability to mobilize large boulders that otherwise prevent channel erosion. Because of this boulder mobilization, GLOF impacts far exceed those of the annual summer monsoon, and GLOFs may dominate fluvial erosion and channel-hillslope coupling many tens of kilometers downstream of glaciated areas. Long-term valley evolution in these regions may therefore be driven by GLOF frequency and magnitude, rather than by precipitation.

scholarly journals Inventory and classification of the post Little Ice Age glacial lakes in Svalbard

2022 ◽  
Author(s):  
Iwo Wieczorek ◽  
Mateusz Czesław Strzelecki ◽  
Łukasz Stachnik ◽  
Jacob Clement Yde ◽  
Jakub Małecki
Keyword(s):  
Little Ice Age ◽  
High Arctic ◽  
Ice Age ◽  
Aerial Photographs ◽  
Glacial Lake ◽  
High Mountain ◽  
Lake Area ◽  
Glacial Lakes ◽  
Mountain Areas ◽  
Outburst Floods

Abstract. Rapid changes of glacial lakes are among the most visible indicators of global warming in glacierized areas around the world. The general trend is that the area and number of glacial lakes increase significantly in high mountain areas and polar latitudes. However, there is a lack of knowledge about the current state of glacial lakes in the High Arctic. This study aims to address this issue by providing the first glacial lake inventory from Svalbard, with focus on the genesis and evolution of glacial lakes since the end of the Little Ice Age. We use aerial photographs and topographic data from 1936 to 2012 and satellite imagery from 2013 to 2020. The inventory includes the development of 566 glacial lakes (total area of 145.91 km2) that were in direct contact with glaciers in 2008–2012. From the 1990s to the end of the 2000s, the total glacial lake area increased by nearly a factor of six. A decrease in the number of lakes between 2012 and 2020 is related to two main processes: the drainage of 197 lakes and the merger of smaller reservoirs into larger ones. The changes of glacial lakes show how climate change in the High Arctic affect proglacial geomorphology by enhanced formation of glacial lakes, leading to higher risks associated with glacier lake outburst floods in Svalbard.

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